In the modern dental operatory, a powered chair is provided to enable a dentist, or dental assistant, to adjust the chair components into selected positions simply by pressing control buttons. Thus, the chair seat may be raised or lowered to provide an entry/exit position for ease of patient ingress and egress, and the chairback may be pivoted relative to the seat, depending upon the particular preference of the health professional and the procedure to be performed. Early in their development, such chairs were customarily preprogrammed at the factory to assume particular positions, but now some have the capability of being adjusted by the health professional to suit his/her particular preferences.
For instance, U.S. Pat. No. 4,168,099 issued to Jacobs discloses an examination chair particularly suited for use in gynecological examinations. The chair is preprogrammed at the factory to assume automatically a selected one of several standard gynecological examination positions. A footswitch is utilized to actuate the chair control mechanism to effect automatic operation. The chair does not appear to be capable of being programmed in situ by the health professional.
Early attempts to enable chairs to be adjusted in situ included control systems which operated by timing the operation of motors to bring the various chair components into preselected positions. A stated drawback of this approach was the imprecision with which the chair components could be positioned due to the lack of a positive indication of chair position relative to a programmed set point.
The aforementioned drawbacks were stated to be overcome by the control mechanism disclosed in U.S. Pat. No. 4,128,797 to Murata. In Murata, the chairback is provided with a series of control switches, including some manual positioning switches for operating the chair manually, a set switch, and an automatic positioning switch. Sensors are provided for detecting the positions of the various chair components to provide a memorized position when the set switch is actuated at a visually-observed chair position, so that when the automatic switch is actuated, the chair will move precisely to the pre-set position. A drawback of the chair disclosed in Murata is the use of electric motors and higher than desirable voltages in association with the chair sensors to provide the desired control inputs and motions.
In at least one currently commercially available programmable adjustable chair, a recessed set button is provided in a control console at the base of the chair to program a chair position. As a result, when the chair has been adjusted to a preselected position, using manual positioning switches, the health professional must kneel down on the floor and press the button with an implement to input the pre-selected chair position. While this chair may function satisfactorily for its intended purpose, this method of automatic programming is inconvenient to the health professional and, therefore, less than completely desirable. Furthermore, while a footswitch is provided for use in moving the chair components into various positions, the footswitch utilizes a rocker actuator which is not sealed against liquids that might be spilled onto the floor of the operatory adjacent to the footswitch and such a switch does not afford omnidirectional actuation.